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Thread: Flash output

  1. #1

    Default Flash output

    Is there anyway to know how much your flash output adds to exposure? For i.e. Lets just say that we were 2 stops underexposed, is there any way to know how much flash output to set that 2 stop?

  2. #2

    Default Re: Flash output

    Quote Originally Posted by SecretElement View Post
    Is there anyway to know how much your flash output adds to exposure? For i.e. Lets just say that we were 2 stops underexposed, is there any way to know how much flash output to set that 2 stop?
    Yes, set your flash to +2. :P

    Aside from that, your flash will automatically calculate it - as for manually setting a power level, this would depend on the flash GN, as well as the distance to the subject, etc.

    Many online resources for you to read, some have calculators. I googled for "how to calculate flash exposure" and got tons of results. May I suggest you try a bit of self-study first?

    How to Calculate Flash Exposure TheodoorThomas

    PhotoJournalism: Understand basic flash exposure

    Camera Flash: Exposure

    Where can I buy a "flash exposure calculator" or how can I make one ? - Yahoo! Answers


    And many many many more.
    Alpha

  3. #3

    Default

    How do I set it to plus 2? Isn't it by 1/x? Sorry haha I googled the wrong thing

  4. #4
    Moderator catchlights's Avatar
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    Default Re: Flash output

    you need to find out the GN of your flash (read your user manual), the zoom head setting, any diffuser on? subject to flash distance, than you able to calculate flash output of manual mode,

    but if your flash is on TTL mode, the flash will meter the scene and adjust the output accordingly, so there is noway to find out who much the actual output, as it is base on scene to scene.


    you can use a flash meter, but it only work on manual flash mode, as the pre-flash will be recorded by the flash meter and that is not an actual reading.





    hope this help.
    Shoot to Live, Live to Shoot
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  5. #5
    Moderator catchlights's Avatar
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    Default Re: Flash output

    when your flash output is under by two stops,


    add plus two will only work if you are shooting a scene has a lot of white in it, the white will fool the camera meter, so you need to adjust the compensation to override it.

    But it will not work when you are already out of range, as the flash already given it maximum output, adding two or more stops will not able to squeeze out any more output from the flash.
    Shoot to Live, Live to Shoot
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  6. #6
    Moderator Octarine's Avatar
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    Default Re: Flash output

    Quote Originally Posted by SecretElement View Post
    How do I set it to plus 2? Isn't it by 1/x? Sorry haha I googled the wrong thing
    Set to '+2' is called FEC - Flash Exposure Compensation. Described in your camera manual. A setting that is coupled to exposure metering of your camera.
    Setting of '1/x' refers to manual setting of flash output power, where '1/1' is maximum output.
    EOS

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